Products obtained by press-forming (referred to as “press-formed products”) are heavily used in various fields, such as vehicle, home electronics, household furniture and general merchandise fields. A press-formed product can be obtained in general by expanding or drawing a metal sheet, which is clamped by a circumference edge portion of a die and a blank holder (referred also to as “anti-wrinkle holder”, etc), between a forming concave of the die and a forming convex of a punch so that the metal sheet is plastically deformed into a desired shape.
By performing such press-forming, members having a complex shape can efficiently be mass-produced. However, when hot-press forming is employed to produce a certain product such as deep-drawn product in which the amount of plastic deformation of the metal sheet is large, some troubles such as breakage and fracture may easily occur at a particular local area to deteriorate the formability. Various proposals have been made to improve the formability, and relevant descriptions are disclosed in Patent Literature (PTL) below, for example.